Field note. The human keeps a cluster of small metal teeth on a ring and touches them more often than it touches its own offspring.
The cluster is worn at the entrance to every enclosure. Each tooth corresponds to one barrier. The human cannot enter its own sleeping-box, its motion-pod, its work-hive, without presenting the correct tooth to the correct slot and rotating. I have observed this ritual four hundred times. The human does not consider it strange that it has voluntarily locked itself out of every space it owns.
The cluster produces a sound. The human relies on this sound. When the sound is absent, the human enters a state of acute distress: it strikes its own outer coverings repeatedly, upends containers, addresses no one in an elevated pitch. The teeth are usually located within reach of where the panic began.
Note the additional objects welded to the ring. A plastic effigy of an animal. A flat card that grants entry to a food-warehouse. A miniature light. None of these open barriers. The human attaches them anyway, so that the tool of exclusion becomes also a small hanging shrine.
Most curious: when a human surrenders one tooth to another human, the receiving human goes very still. Something passes between them that the metal cannot account for. I have logged this as a malfunction pending further study. The tooth is identical to the others. The reaction is not.
Conclusion, provisional. The species has built a world it must be granted permission to enter, and then it grew fond of the permission.